enumerator.c: Introduce Enumerator::ArithmeticSequence

This commit introduces new core class Enumerator::ArithmeticSequence.
Enumerator::ArithmeticSequence is a subclass of Enumerator, and
represents a number generator of an arithmetic sequence.

After this commit, Numeric#step and Range#step without blocks
returned an ArithmeticSequence object instead of an Enumerator.

This class introduces the following incompatibilities:

- You can create a zero-step ArithmeticSequence,
  and its size is not ArgumentError, but Infinity.
- You can create a negative-step ArithmeticSequence from a range.

[ruby-core:82816] [Feature #13904]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64205 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 0 deletions

diff --git a/internal.h b/internal.h
index 7047eb4c3d..81c556c0be 100644
--- a/internal.h
+++ b/internal.h
@@ -1995,6 +1995,11 @@ enum rb_int_parse_flags {
 };
 VALUE rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits, int base, int flags);
 
+/* enumerator.c (export) */
+VALUE rb_arith_seq_new(VALUE obj, VALUE meth, int argc, VALUE const *argv,
+                       rb_enumerator_size_func *size_fn,
+                       VALUE beg, VALUE end, VALUE step, int excl);
+
 /* error.c (export) */
 int rb_bug_reporter_add(void (*func)(FILE *, void *), void *data);
 NORETURN(void rb_unexpected_type(VALUE,int));